Refrigerated table for microtomes



Feb. 24, 1953 c. R. TURNER 2,629,230

REFRIGERATED TABLE FOR MICROTOMES Filed July 28, 1950 ,;-IIIIIIIEEWWI/ll? \N 7% JNVEN TOR. CECIL ,EANDOLF TUE/V58 am MM! "tioning; a iFreshtissue may be directly transferred to the table of a microtomewithout previous imbedding, "and sectioned after freezing. This affordsa ready Patented Feb. 24, 1953 UNITED: STATES PATENT OFFICE 2,629,230REFRIGERATED TABLE FOR MIoRo'roMEs Cecil Randolf Turner, Cleveland,Ohio, assignor to Maurice J. Bishko, Cleveland, Ohio Application July28, 1950, Serial No. 176,267

t This invention relates to freezing devices and particularly to acyclic freezing table for microtomes. i

Conducive to a better understanding of this invention, it may be well topoint out that the freezing ofsoft tissue so that it may be renderedrigid enough to be cut into thin sections is an old expedient in the artof microscopic secmeans of rapidly determining the nature of a giventissue, and isvery serviceable, especially to the pathologist.The'freezing agents may vary from ordinary ice and salt brine to highlyvolatile fluids such as liquid carbon dioxide,

ether and rhigolene.

In every case the freezing agent is used only once and is' permitted toescape after it has served its purpose. This is especially true ofcarbon dioxide, which is the refrigerant most commonly used. i

In a large pathology laboratory running hundreds of tissue examinationsa day, one or more cylinders of liquid carbon dioxide may be used.

This is not only a continuing expense but facilities must be providedfor the periodic replacemerit 'of the heavy cylinders as they becomeempty. l

The primary object of this invention thereforeis to provide afreezingdevice for microthrough its liquid and vapor object readily andconveniently and ofholding it firmly in place.

A further object is to provide a freezing surface whose rate oftemperature change can be accurately regulated so that the tissue cellsare i not distorted by icecrystals which form when i the freezing rateis uncontrolled. Still another object is to providean apparatus of thisclass which is very simple and economicalof construction, easy tooperate, ef-

ficient in its action and which will not readily deteriorate or get outof order.

' With these and other objects in view as W111 appear hereinafter, myinvention consists of oertain novel features of construction,combination and arrangements of parts andportions as will beihereinafter described detail and particularly set forth in the appendedclaims, refer jenc'e being had to the accompanying drawing refrigeratedtable for microtomes;

size is 1 inches in diameter.

I Figure 3 is a bottomview of thetop wall taken substantially along theline and in the direction of the arrows 3-3 of the Figure 2; I

Figure 4 is a top plan view of the device; and

Figure 5 is a schematic view showing the refrigerated table connected inthe closed compressor circuit.

Referring to the drawing there is seen in the Figures 1 and 2 arefrigerated table made in accordance with this invention.

The body It is made of a suitable non-corrosive metal such as brass orstainless steel andhas sufiicient wall thickness to function properlyunder the pressures used as set forth hereinafter. The body ll] may beof any desired shape but is preferably cylindrical in form for reasonsof ease of machining, a suggested A smooth stem IT is formedintegralwith the bottom of the .body It! and is intended to interfita matingsocket in the base of the microtome with which the table is intended tobe used. The table is held in an upright position by the stem [1 and iseasily removable from the microtome socket when desired.

The upper part oflthe body is bored out to form the cavity I I havingside and-bottom walls. Reference. numeral l2. indicates aninletjboreformed along the vertical axis of the body I0 and having an inlet nipplel3-seatedin its hori- The preferred orificial diameter, in the modelshown, being .007 inch.

Reference numeral l4 indicates an outlet nipple mounted in the side wallof the cavity II. The nipple I4 is connected to an outlet tube 34including a control valve 35 leading to ervoir 3 l.

the compresser pump 30, condenser 36 and res- Nipple I3 is connected tothe outlet of the reservoir 3| through the inlet tube and valve 32 and33 respectively.

3 top of the circular side wall of the cavity H and forms a closuretherefor.

The cover plate is relatively thin and together with the side and bottomwalls forms a cavity II that is approximately .625 inch deep in thepreferred form illustrated. Reference numeral indicates a centrallylocated dependent solid conical diffuser formed integral with the bottomsurface of the cover plate 20'. The mass of the solid metal cone 2! ismade equal to or greater than the mass of the table 29, apart from thearea immediately above the cone. The table being made very thin so thatthe heat transfer from the specimen resting thereon will be practicallyinstantaneous. A pluralityof a'rcuate equi-spaced dependent fins 22, 23,24, 25, 26 and 21 extend from the bottom surface of the plate 20 andradiate toward the periphery thereof from the cone 2| as a center. Theplate 20 has a spiral groove 28 cut inv its upper surface as shown inthe Figure 4. The plate 28 is brazed or welded in place as. shown in theFigure 2. When the plate 20 is in place the apex of the diffuser cone 2|isv aligned with the orificial opening It of the nozzle l5.

The refrigerant used may be methyl chloride or one of the so-calledFreon refrigerants such as:- Freon-12 (.dichloro-difiuoro methane),Freon-22 (d'ifluor-monochler methane) or Freon-114 (dichloro-tetrafiuoroethane).

In the case of Freon-12 approximately 1 /2 pounds of the liquid Freon isused in the closed refrigeration system.

The Freon gas is li'quified by the pump 30 and stored in the reservoir3! from whence it is delivered to the jet tube l5 at a pressure of 90pounds 1 s. i. Vapor present inthe cavity H is. removed under suctionthrough the tube 34 to the suction side of the compressor 30 as is wellknown to those skilled in the art.

In the freezing of tissue a few drops of water. are placed on the centerof the cover plate 20 and the specimen to be" frozen is positioned onthe plate on the water. The valve 35 is adjusted so that the properpressure is created in the chamber cavity 1 It consistent with thetemperature desired.

23" of mercury, vacuum 75 Fahrenheit.

"154 of mercury. vacuum. 50 Fahrenheit. .6 lb. of pressure prszi; 20Fahrenheit.

9.2 lbs. of pressure p..s. i. 0 Fahrenheit.

In the case of Freon-22, the values are as follows:

' 18.5of mercury, vacuum 75 Fahrenheit.

6.0" of mercury, vacuum 50 Fahrenheit. 103 lbs. pressure p. s. i. 20Fahrenheit. 24.2 lbs. pressure us. i. 0 Fahrenheit.

After the desired pressure in: the cavity is established with referenceto the temperature desired, the valve 33 is opened and the liquidrefrigerant is introduced into the cavity H-by being forceably ejectedfrom the nozzle I5 in the form of a jet directed against the apex of,the

, diffuser cone 2!.

The conical shape of the deflector 2| causes the liquid stream to bedispersed at right angles .and radially over! the undersurface of thecover 20'. Uniform distribution is further insured b the radial fins 22to 21 inclusive. The fins also increase the surface area of the plate 20and hasten the heat-transfer rate, thereby bringing about the quickcooling of the tissue positioned on the upper surface of the plate 20.

The water associated with the tissue and laying in the spiral groove 28quickly freezes. The spiral configuration of the groove 28 providesanchorage against shearing. stress. in. all directions so that the.table may be oriented in any direction with reference to the microtomecutting knife. The relatively great mass of the deflector cone withreference to the thickness of the table top. 20' provides for less] heattransfer at the point where the greatest quantity of liquid ismomentarily available for evaporation. This makes for a uniformtemperature over the entire table top surface. without any localizedcold spots. The vaporized refrigerant is drawn back into the compressorthrough the tube 34 and re-liquified. This closed circuit uses the samerefrigerant over and over; therefore making for economy of operation.

By varying the pressure in the cavity H, as outlined in the tableshereinabove, the. rate; of vaporization and consequently the rate offreezing of the tissue can be accurately controlled as the freezingprogresses. Thus the splitting and distortion of tissue cells can beprevented.

It is also possible to produce frozen tissues of the proper rigidity tosuit the type. of cutting knife used, thereby making for the moreaccurate, speedier and economical sectioning of soft tissues.

It will now be clear that there is provided. a device which accomplishesthe objectives heretofore set forth. While.- the invention has beendisclosed in its preferred form; it is. to beunderstood that thespecific embodiment thereof as described and illustrated herein is notto be considered in a limited sense as there may be other forms ormodifications of the: invention which should also be construed tov comewithin. the scope of the appended claims.

I claim:

l. A refrigerated table. for microtomes, comprising incombinationJa-yapm tight expansion chamber having top, bottoma-nd sidevwalls, the said top wall being heat conductive and having a plane uppersurface adapted to support tissue to be frozen, a solid conical diffuserpositioned centrally of the underside of the top: wall and formedintegral therewith, the mass of said cone being greater than the mass ofthe top: wall exclusive of that area immediately above the cone, meansfor projecting a jet; of liquid refrigerant against the said solidconical diffuser, and means for maintaining the pressure of the: chamberbelow that of the introduced liquid refrigerant so that theliquidrefrigerant willbe caused to pass into its vapor phase thereby absorbingheat from the chamber top wall.

2. A refrigerated tablefor microtomes, com prising in combination, avapor" tight expansion chamber having top, bottom and side Walls, thesaid top wall being heat conductive and having a plane upper surfaceadapted to support tissue to be frozen, a solid conical diffuserpositioned centrally of the underside ofthe top' wall and formedintegral therewith, the mass of said cone being greater than the mass ofthe top wall exclusive of that area immediately abovethe solid cone, aplurality of dependent fins formed integral with the underside of saidtop wall and extending radially from the cone as a center to theperiphery of the topwall, means for projecting a jet of liquidrefrigerant against the said solid conical diffuser, means formaintaining the pressure of the chamber below that of the introducedliquid refrigerant so that the liquid refrigerant will be caused to passinto its vapor phase thereby absorbing heat from the chamber top wall,and means for recovering the vaporized refrigerant and reliquefying itfor return to the projecting means.

3. A refrigerated table for microtomes, comprising in combination, avapor tight expansion chamber having top, bottom and side walls, thesaid top wall being heat conductive and having a plane upper surfaceadapted to support tissue to be frozen, a solid conical diffuserpositioned centrally of the underside of the top wall and formedintegral therewith, the mass of said cone being greater than the mass ofthe top wall exclusive of that area immediately above the solid cone, aplurality of equi-spaced arcuate dependent fins formed integral with theunderside of the top wall and extending radially from the solid conicaldiffuser as a center to the periphery of the said top wall, means forprojecting a jet of liquid refrigerant against the apex of the saidsolid cone diffuser, means for maintaining the pressure of the chamberbelow that of the introduced liquid refrigerant so that the liquidrefrigerant will be caused to pass into its vapor phase therebyabsorbing heat from the chamber top wall, and means for recovering thevaporized refrigerant and reliquefying it for return to the projectingmeans.

4. A refrigerated table for microtomes, comprising in combination, avapor tight expansion chamber having top, bottom and side walls, thesaid top wall being heat conductive and having a plane upper surfaceadapted to support tissue to be frozen, a solid conical diffuserpositioned centrally of the underside of the top wall and formedintegral therewith, the mass of said cone being greater than the mass ofthe top wall exclusive of that area immediately above the solid cone, aplurality of equi-spaced arcuate dependent fins formed integral with theunderside of the top wall and extending radially from the solid conicaldiffuser as a center to the periphery of the said top wall, an inletnozzle mounted on the bottom of the chamber below the said solid cone,and having its orifice aligned with the apex of the cone, an inlet tubecarried by the said nozzle, an outlet nipple in the side wall, an outlettube carried by the said nipple, a closed compression system connectedbetween the said inlet and outlet tubes and including a fixed volume ofrefrigerant, and valving means for selectively adjusting the pressureratio between the liquid and vapor phases of the refrigerant whereby itsrate of vaporization in the expansion chamber may be controlled.

CECIL RANDQLF TURNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

